Decontamination of an Arbitrary Network from Multiple Black Viruses

In networks supporting mobile agents, a particular threat is that posed by the presence of a black virus (BV), a harmful entity capable of destroying any arriving agent, and of spreading clones to neighbouring sites. A BV can only be destroyed if at the same site there is an anti-viral agent; but, if the BV is already active when encountering the agent, it spreads clones to all the neighbouring sites. The problem of locating and permanently eliminating all such harmful presences has been studied both in special classes of regular network topologies, and in networks of arbitrary and unknown topology; however, in all these studies, it was assumed that there was a single BV in the system. In this paper we consider the case of multiple BVs. We present fully distributed decontamination procedures that operate with no a priori knowledge of the network topology, nor of the number and location of the black viruses.